(Topic ID: 211373)

Tech: Bally Medusa Start Up / Error Reporting?

By EEE

6 years ago

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Latest reply 6 years ago by EEE
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Linked Games

Medusa Bally, 1981

I have a Medusa that is showing an intermittent start up and game play behavior.

It seems to be related to the zipper flipper assembly.

Occassionally when I turn on the machine, the knocker fires. I have been able to go into solenoid test and as they are cycled, the small pull in or retun to normal spacing for the upper zipper flipper goes off and the knocker fires again.

Is that a trouble shooting assistance?

I also note that the solenoid test cycle will stop at that coil and not fire the other coils further into the test.

Any of you gurus have something to say about this mystery?

Rebuild MPU J4, and SDB J3 and J4 headers and connectors, if it hasn't been done already.

OP
Quoted from EEE:
I have a Medusa that is showing an intermittent start up and game play behavior.
It seems to be related to the zipper flipper assembly.
Occassionally when I turn on the machine, the knocker fires. I have been able to go into solenoid test and as they are cycled, the small pull in or retun to normal spacing for the upper zipper flipper goes off and the knocker fires again.
Is that a trouble shooting assistance?
I also note that the solenoid test cycle will stop at that coil and not fire the other coils further into the test.
Any of you gurus have something to say about this mystery?

its not unusual for the continuous solenoids to briefly pull in at power up and during the PIA test. The pulse is so fast you normally don't even notice anything from the solenoid coil, but in the test fixture the LED indicators will give a fast blink. The sound boards usually chirp at the same time.

Solenoid test should run continuously and start over at 1. Is the game locking up when it fires a certain coil? If so make sure it has the EMF blocking diodes. I am not familiar with zipper flippers in a game like medusa.

Also Medusa's manual counts 24 solenoids. That means a solenoid expander relay is in play. The expander relay PCB being mounted on the playfield cracks the connector solder joints. Make sure the connectors are good there and that expander lamp and relay are clicking on and off during lamp test. You should hear it click and the expander lamp will turn on during solenoid test too. Expanded solenoids are all done at the end (typically i think, at least they are on EBD).

If coils are firing out of the proper order it is usually a MPU j4 to driver j4 connector issue like Cody mentioned above.

You called it Andrew. Cracked solder joints on the solenoid expander board. Reflowed them and everything seems to be working fine.

Thanks to both of you!

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